I have always connected my Windows 7 64-bit laptop and my Windows XP SP3 desktop through WiFi by setting the IPv4 address to 192.22.22.x (x = 1 for laptop and x=2 for PC). However, since this week I am not able to do so.

When I set the IPv4 on my Windows 7 laptop and press OK it doesn’t seem to save. When I check the IPv4 address again, it’s blank. Please tell me a way to fix this. I am not able to do file sharing.

Hi
A quick fix is to uninstall the driver and then reboot the system. Let the OS re-install the driver and the system should be able to get a new DHCP IP. If that doesn't happen then either the device is bad or something is wrong with the router in question. Either power cycle the router or do a reset.

: How to Change IP Address in Windows 7http://www.computing-tips.net/Change_IP_Address_Windows_7/
While changing IP address in windows 7, you will find out that setting two adapters with the same Gateway IP wall cause windows to reject the new configurations. Similarly, if the change is being made by a DHCP server, windows 7 may not pick the new DHCP configuration being issued

OK, so go back to the services console, double click the DHCP service, choose the log on tab at the top of the dialog box, make sure that the radio button near the words "This account" is selected, then click the browse button, then the advanced button on the next dialog box, then the find now button on the next dialog box, then in the "Select User" dialog box near the bottom, select the "LOCAL SERVICE" group and OK, your way back out of there and then see if you can start the service..

Disabling HomeGroup:
Step 1:1)Start by clicking the Start Orb and hitting Control Panel2)Click on Network and Internet then Click on HomeGroup3)In the Change HomeGroup Setting click on Leave the homegroup4)Click on Leave the homegroup5)You’ll get a confirmation message that the HomeGroup has been left. Click Finish6)HomeGroup in the Control Panel should now sport the Create a homegroup button. Exit Control PanelStep 2:Now you need to disable the HomeGroup services. 1)click on the Start Orb and type; services.msc. Click on services at the top of the Start Menu.2)Now, scroll down the services list until you see HomeGroup Listener & HomeGroup Provider. Double click on HomeGroup Listener.3)In the Startup type drop down menu, click Disabled. Under Service status, click on the Stop button. Click Apply then OK.4)Repeat this step exactly for HomeGroup Provider.5)The HomeGroup feature is now disabled.

also possibly This is probably a services issue....

Control Panel -> Administrative tools -> Services.

Set "DHCP Client" to Automatic
Set "DNS Client" to Automatic

In the adaptor settings where you've been keying your IP...
Set it to "Obtain IP Address automatically" and "Obtain DNS server Address automatically"...

Restart your system.

In your router/switch ... check settings and be sure that DNS and DHCP are enabled there too. then reboot both pc.

Change Your Dynamic IP Address

Following is supposed to change your dynamic IP Address. Open notepad and type: